SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '031192ea2afb81aafa5706321327826f0fa256c17538242d726c50a0f8e4ef2f' 
  AND token = 'n4cPZio3zQSxCEcMMMkHpJNZsi92bDNpk5XpNmPcPxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}